Generally, an Electronic Control Unit (ECU) of an Electrical Power Steering (EPS) system controls the steering of a vehicle by detecting steering torque according to the manipulation of a steering wheel of a driver through a torque sensor.
In the torque sensor of the EPS system, an output waveform of the torque detecting coil is sampled through a sampling pulse circuit.
The phase and amplitude of the output signal vary according to an impedance variation of the torque detecting coil. When a phase variation occurs due to environmental effect such as a temperature variation, or the like if a precise sampling of the signal is not executed, reliability of the torque sensor deteriorates by, for example, a distortion phenomenon of the torque detecting signal.